The invention relates generally to communication devices, and particularly to paging devices including cryptographic messages and paging device management thereof.
Paging devices are evolving into information terminals, providing more than merely a "beep" or a telephone number to be called in response to the page. In particular, paging devices can display alpha-numeric pages bearing a variety of messages. Also, by prearrangement with a message source, meaningful information can be encoded into the form of a telephone number or given pattern of digit presentation to convey, by such prearrangement, meaningful information beyond a telephone number to called. Security with respect to information delivered to a paging device is desirable because paging devices can receive for display and storage confidential information, e.g., bank account balance information or a variety of other information the receiver considers confidential.
Security with respect to message display and device access in a paging device has been proposed wherein the user enters a password before the paging device displays certain designated messages, or before the device exits a "lockout" mode. For example, see U.S. Pat. No. 5,146,217 issued Sep. 8, 1992 to Holmes et al and entitled SELECTIVE CALL RECEIVER HAVING CONFIDENTIAL MESSAGE READ PROTECTION. Unfortunately, such arrangement does not protect the confidentiality of messages when broadcast by radio signal to the paging device. By modifying radio receiving and data processing equipment to match the broadcast protocol of a given paging system, an adversary can simply eavesdrop on the radio signal broadcast and obtain confidential information.
Paging devices are generally small, miniaturized radio receiving devices including, to the extent possible in such miniaturized devices, certain user interface resources, e.g., a display and several control buttons. Unfortunately, such control buttons are generally a limited resource in a miniaturized paging device. For example, paging devices have been successfully miniaturized into the form of a wristwatch paging device. Under such extreme miniaturization, few control buttons are practical. Accordingly, requiring that the user engage in complex user interface activity becomes unacceptable with limited control button resources. As may be appreciated, any features added to a paging device should make the most efficient use possible of existing paging device resources, and preferably not require additional device resources.
The subject matter of the present invention addresses the problem of security in a paging system by providing a mechanism for secure message transmission and management with low user interface overhead allowing implementation with limited control button resources.